While this mission may seem aimed at combating a far-fetched hazard, defending the planet from asteroids is incredibly important. Investing in planetary defense missions like DART brings us closer to preventing catastrophic events that have changed the course of life on Earth many times in the past.
If NASA is going to invest taxpayer funds into a low-probability, a high-impact threat like deflecting asteroids, a good offense is better than a strong defense. This means developing an aggressive early warning system and even being able to pulverize potential intruders. Asteroid defense is an expensive undertaking, so let's get it right.